October 2003 AGGMAN Operations

Training employees to operate and maintain conveyors improves efficiency of both the belt and the operation.

A conveyor belt is essentially a giant rubber band, stretched tight and threaded through a maze of obstructions and pinch points. This band is then burdened with a heavy load and pulled at high speeds. The forces applied are significant and potentially dangerous. These forces create risks to personnel who are working on or in the vicinity of belt conveyors.
Part of the problem is that conveyors have become “part of the landscape.” They are not seen as a hazard, but rather as a fact of life — like driving a car or using a telephone. The average employee does not see the risks inherent in the conveyor because they have not been trained to observe (and avoid) the risks.
In CFR Part 46 and 48, the Mine Safety and Health Administration (MSHA) requires training for all miners. Newly hired workers must receive 24 hours of specified training. In most cases, four hours must be given before work begins, while the remaining 20 hours must be given within 60 days while working under close supervision. All miners must receive eight hours of specific refresher training each 12 months.
The introductory 24-hour training program typically includes an introduction to the work environment, hazard recognition, miners’ rights, electrical hazards, and the health and safety aspects of assigned tasks. However, there is no specific equipment training mentioned, and that means that there is no specification for conveyor training. However, when one looks at the number of conveyor-related accidents and fatalities, it becomes evident that the existing training programs have accomplished very little in preventing conveyor accidents.

Accident analysis
A report entitled “Powered Haulage Conveyor Belt Injuries in Surface Areas of Metal/Nometal Mines 1996-2000,” by Harvey Padgett, a mine safety and health specialist with MSHA’s Office of Injury and Employment Information, noted that over a four-year period, there were 459 reported injuries ranging from fatalities to injuries with restricted work activity. Of these 459 accidents, 13 were fatalities and another 22 were reported as permanent disabilities. The statistics were for metal/nonmetal mines in the United States.
It has been estimated that the average cost of a fatality in a mine is $1.02 million. This figure, originally published in 1986, includes the cost of medical expenses, worker’s compensation, accident investigation, loss of family income, and lost production value. The cost for underground accidents of less severity was estimated at $237,000 for permanent disability accidents and $5,000 for lost-time accidents.
Of the reported injuries, 192 — or 42 percent — occurred when the injured worker was performing maintenance, lubrication, or checking the conveyor. Ten of these incidents were fatalities. Another 179 reported injuries — or 39 percent — occurred while the subject was cleaning and shoveling around the conveyors. Three of these incidents were fatalities.
This may be due to a tendency to send “the new kid” — the least experienced, most recently hired — out to do the job that nobody wants: to clean up around moving belt conveyors.
The most common reported cause of accidents around conveyors is getting caught by the moving conveyor belt or pulley. This accounted for 290 of the 459 injuries and 10 of the 13 fatalities. The following types of activities were reported:

Looking at this record, it is easy to see that both experienced and new miners are susceptible to injury or death. This is true because there has been no specific training on the hazards and the correct procedures when working around conveyors.

Training prevents accidents
What is the answer to prevent conveyor belt accidents? Well, it is obvious that dedicated training should be provided to all employees both experienced and new prior to any work being performed around a conveyor. This comprehensive training should include the following:

In fact, training in conveyor operations provides the best of both worlds. It presents an opportunity to provide training on worker safety that will also improve a mine’s operating efficiency. By training workers on how to better maintain and operate conveyors, you can improve the results and reduce the opportunities that require service and frequently lead to accidents. This double benefit provides additional credibility in operations where safety training may be met by an “eyes rolled back in the head, you’re wasting my time” look from employees.

General safety practices

Equipment related to or interlocked with a conveyor must also be locked out before conducting maintenance or other work on or around a conveyor.

Conveyor safety starts with the new employee. Prior to assigning a new employee to the task of working around a conveyor, the employee should attend a minimum of four hours of classroom instruction specific to belt conveyors. And don’t forget the veteran employees. Keep in mind that the senior employee has probably had little or no training about belt conveyors or conveyor safety.
Many operations forbid working on the conveyor when it is running, but the same operations require working around the conveyor while it is in operation.
If maintenance or other work needs to be done, the conveyor should be locked out and tagged out. Failing that, extreme caution should be exercised when working in the vicinity of the conveyor system.
Employees should be trained on proper lock out/tag out procedures and the blocking procedures specific to conveyors. Many times, interlocked or related equipment must also be properly placed out of service to totally protect workers from safety hazards.
Richard J. Wilson of the Bureau of Mines Twin Cities Research Center noted the following in a paper, “Conveyor Safety Research,” published in 1982: “Most procedures require locking out the main power switch at the head pulley or control room. As this could be quite some distance from the work site, compliance could require a considerable amount of time and effort. It is not difficult to imagine maintenance personnel rationalizing that it is all right to quickly perform some routine repair work without locking out the belt when to implement the procedure would take much longer than the job itself.”
It is important that workers know the location for all emergency stop buttons or shut down pull ropes. That way, if something goes wrong, the employee will know how to quickly shut down the system and reduce the chance of injury.
Long hair should be tied up and placed under a scarf or hardhat to prevent being caught in moving conveyor parts. The current style of loose, baggy clothing can also be a cause of conveyor accidents. Something as simple as a hooded sweatshirt can become entangled in a conveyor belt with life-threatening consequences.
Personal protection devices should also be provided. It is the responsibility of the employer to provide the dust protection apparatus suitable for a dusty environment, but it is the responsibility of the employee to use the provided equipment. This includes hard hats, hearing protection, and dust masks.
Don’t overlook even something as simple as proper shoveling techniques. This includes never shoveling onto a moving conveyor belt. If a shovel would get caught in a moving belt, the shovel could either spear the handler or tear off his arm. Even when a belt is traveling as slowly as 150 fpm, the mind cannot respond quickly enough to “let go” without injury.

Belt conditions

Training should include explanations of belt conditions — such as belt cupping shown here — and how to identify them.

Most conveyor accidents occur because of material spillage. Never shovel spilled material back on to a moving conveyor belt. If the shovel gets caught in a moving belt , it could spear the worker or tear his arm off.

Training should include a thorough understanding of belt conditions. By understanding different belt conditions, exposure to conveyor accidents can be reduced. Training should include explanations of the following:

There is always a reason why a belt does not track properly: misaligned components, belt conditions, material accumulation, off-center loading, weather, or a combination of factors.

The majority of conveyor accidents analyzed occurred because of material spillage. Training employees on where fugitive material escapes a conveyor and correcting the problems may go a long way toward reducing exposure to conveyor accidents. Typical spillage sources include:

Eliminating problems in conveyor operation that require employee attention, such as conditions that cause material spillage, will improve the efficiency of both the conveyor and the entire operation.

Belt tracking — the manipulation of conveyor components to get the belt to run in the center of the structure — has been regarded as a sort of “black art” known only to senior employees. In fact, however, belt tracking is a science. There is always a reason why a belt does not track. Educating employees on the correct method of tracking and reasons for tracking failure can reduce the exposure to conveyor belt injuries.
Belt tracking is a three-step process. First, a visual inspection must be made to identify the reason (or reasons) why a belt is not tracking properly. There are numerous problems that may cause a belt to wander. These could include the alignment of various conveyor components such as the structure, the rolling components, idlers and pulleys, or the gravity take up. They could include belt condition with problems such as belt camber or belt cupping. Mistracking could be caused by material accumulation in a chute or off-center loading patterns. It could even relate to the weather, or be a combination of these factors.
The second step is usually the most difficult. The conveyor must be shut down, and the problem(s) identified in the first step must be corrected. Most people look for some magic, quick fix. There is none. Many times, management will not shut the conveyor down long enough to correct the problem(s). This certainly increases the risk of injury if the worker is required to track a belt that cannot be tracked without the proper corrections.
The last step is to make the physical adjustments, starting at the lowest tension area of the belt (directly behind the drive pulley) and working toward the higher tension areas of the belt. Typically, the solution calls for turning the rolling stock slightly in an attempt to steer the belt into the proper path.

Conclusions
Can we totally eliminate conveyor accidents? Probably not, but we can work toward zero accidents by:

Bear in mind that the cost of one accident will easily exceed the cost for either the use of an outside training program or an in-house training person. The cost of a fatality might be the total career salary for a full-time safety trainer. The costs for effectively training an employee to operate and maintain conveyors safely will pay for itself very quickly.
Eliminating the problems in conveyor operation that require employee attention will, in fact, improve the efficiency of both the conveyor and the entire operation. That is a double payback.

Successful Training
Selecting the correct facility and time for the training is essential to successful training. The facility should be comfortable, well lit, the correct size, and contain the correct audio-visual aids. Conducting training in a lunchroom where people continually come in and out is disruptive. Look for a space that is free from interruptions.
The best time to perform training is the first thing in the morning when employees are fresh. The room should be sized to allow group breakouts, but not so large that people can “hide” in the back. The number of chairs and tables should closely match the number of attendees. Note-taking material should be set at each station.
Training should be performed by a professional resource who has experience in conveyor operations, equipment maintenance procedures, and safety requirements. The instructor should be knowledgeable on the “how” and “why” of conveyor accidents. And certainly, the instructor should have excellent training materials geared specifically toward conveyor belt training. Using a “canned” safety presentation may not cover specific conveyor belt training.

Larry Goldbeck is a the manager of conveyor technology for Martin Engineering. He holds four patents on components to help conveyors operate more cleanly, safely, and productively.

Success in the Field

Successful Control of Sand Gradation

A specially designed sand plant gives an Ohio river dredge renewed life to meet tighter specifications.

A low-head, semi-portable EIW sand classifier and fine material washers produce finished, specification sands from IMI Delta’s dredge on the Ohio River.

From mile 804 on the Ohio River near Henderson, Ky.; mile 858 at Shawneetown, Ill.; and mile 870 at Caseyville, Ky.; IMI South LLC’s Delta Division dredges river-bottom sand and gravel for local markets. Using a single suction-head dredge with on-board screening and sand classification, the company supplies several specification sands — to the Corps of Engineers and to customers in two states — made from sometimes variable deposits. Gradation control is critical to successful operation.
“We may produce Kentucky or Illinois state specs, or we may have a customer looking for ASTM C33,” says Robert Stone, general manager of IMI Delta. “Or, if we happen to be working through a contractor for the Corps, (they) may have their own set of specifications.
“Specifications are getting tighter and we’re only as good as the deposit we’re over,” Stone says. “With the equipment in place working and giving our people the capability to make the adjustment, it is possible for us to make more minute cuts in gradation and yield a better product.”
Prior to this spring, however, sand gradation control was more difficult. The dredge, originally constructed by Delta Materials — before IMI purchased the company in 1999 — contained components from several other dredges, including a 1965 Eagle Iron Works (EIW), manually controlled sand plant.
“The scalping tank had deteriorated to the point where it was not a good proposition to rebuild,” Stone says. “The sand screws were in pretty good condition, but we wanted to upgrade and be able to obtain the beneficiation that a new unit would give us.”
Controls on the old sand classifier had been replaced with manually adjusted gates on the bottom of the sand discharge stations. In addition to the lack of precision, manually adjusting the gates “put people in harms way over the sand screws,” Stone says.
IMI Delta began conversations with Dawson Horn, senior sales manager at Process Machinery, about upgrading the old sand plant. His initial recommendations would have required cutting all the supports on the 6- x 16-ft. Seco triple-deck screen and raising the structure about 18 in. to accommodate the new unit. After further investigation, Horn recommended a specially designed, EIW semi-portable sand section, including a 40- x 10-ft. water scalping/classifying tank and two 44-in. x 32-ft. single-screw fine material washers. Stone says this plant had an identical footprint to the plant it replaced.
Reversing the placement of the fine material washers improves the center of gravity, which helps keep the dredge level. “Feed height to the tank is lower,” Horn explains. “Any barge-mounting unit needs to be as low as possible to keep the balance in order.”
A 12 x 14 GIW pump sucks material from as deep as 37 ft. off the river bed. Gravel can be recovered on the triple-deck screen and up to 350 tph finished sand product from the classifier. An EIW DialSplit reblending system maintains sand gradation, which is checked in an on-board lab. A heated and air conditioned, 15 x 15-ft. operator’s station contains a console and controls for everything on the dredge, including some the of the winches.
Side conveyors discharge sand to barges on one side of the dredge, gravel to barges on the other side. The configuration allows production of only one specification sand at a time when also producing gravel. There is no aggregate storage capacity on the dredge.

IMI Delta’s “sand flat” barges (195 x 35 x 9.5 ft.) hold about 1,100 tons. Sand is loaded directly from the fine material washers. Company boats deliver empty barges to the dredge and full barges to offload points on shore.

The Bottom Line
IMI South LLC Delta Division renewed the life of one of its Ohio River dredges by replacing a manually controlled sand classifier with a low-head classifier, two fine material washers, and reblending controls. The plant can meet tighter specifications and address the company’s ongoing commitment to improved quality.

To submit a suggestion for a Success in the Field or for more information about any of these stories, contact Aggregates Manager at 330-966-2454, Fax: 330-966-2454 or email at bob@aggman.com

Tech Trends

Improved Impactors Lessen Limits on Use

Wear part composition, maintenance access, and larger feed openings expand the range of economic crushing.

By Bob Drake

If reduction ratio was the only criteria for selecting a crusher, horizontal shaft impactors (HSIs) would be the easy choice. Compression-type crushers — jaws, gyratories, and cones — can’t compete with the 15:1, 20:1, or greater ratios possible from primary and secondary HSIs.
Limitations on the use of HSIs historically have been wear costs and, to a lesser extent, maximum feed size in primary circuits. The latest generation of HSIs, however, have come a long way toward addressing these issues and others. In most cases an HSI probably remains a higher-cost choice for crushing highly abrasive rock, but improvements in wear part metalslurgy and in crusher access for maintenance have extended the range of materials that an HSI can economically process. Larger impactors with expanded feed openings likewise can accommodate larger feed sizes.
Most HSIs today hydraulically open to provide easy access to the rotor, blow bars, aprons, and crushing chamber. Simplified systems for replacing or rotating bars have significantly shortened maintenance downtime.
Interchangeable liner segments for the crushing chamber walls and aprons are now common on HSIs. This results in more complete use of wear material by allowing switching of segments between high- and low-wear positions. HSI designs with three or fewer liner shapes also help reduce inventory costs for wear parts.
Apron adjustment also is easier with hydraulic assist or total hydraulic adjustment.
Following are brief descriptions of a variety of HSIs and the features that are improving their performance while lowering costs. Additional information from each manufacturer is available using the appropriate InfoDirect number and the link on Aggregates Manager’s web site (www.aggman.com).

1. Bohringer
Bohringer, Inc. introduces the Champ 140 CR crawler crushing plant incorporating the company’s RC-14NG HSI. The crusher has a 70- x 57-in. feed opening and a 54-in. crusher discharge conveyor. Plant capacity is rated at up to 750 tph. Bohringer impactors use solid steel, welded rotors with two, three, four, or six rows of blow bars. The bars are held in place with a quick-release wedge lock system. Impact aprons are available in two- or three-stage designs as a one piece casting (monoblock) or fabricated with bolt-on wear plates. The company also offers automatic hydraulic/accumulator apron-adjustment systems. Liner plates of abrasion resistant steel are bolted from the outside for maximum utilization, the company says.
InfoDirect 701

2. Cedarapids
A 52- x 81-in. feed opening on Cedarapids’ 1520 Andreas primary impactor can handle up to 34-in. diameter shot rock, sand, and gravel at rates up to 800 tph, the company says. The 61-in. diameter high-inertia rotor is available with three or four bars. A cast monoblock manganese primary breaker plate is reversible to maximize wear and is adjustable — with optional hydraulic assist — to a 12-in. opening. The secondary breaker plate has interchangeable liner segments, as do the crusher chamber walls. Both breaker plates feature a pivot shaft, allowing quick rotation while in place, Cedarapids says. The crusher’s upper frame has standard hydraulic opening.
InfoDirect 702

3. DBT Mineral Processing
DBT Mineral Processing’s primary crushers are intended for low-silica stone. The skid-mounted roll impactor uses what DBT calls “horizontal flow crushing.” The unit is designed to be fed at grade using a pan conveyor with chains and flight bars to move material in a straight line through the crushing chamber. The rotor is mounted above the pan conveyor and contains eight impact bits, arranged in two rows, mounted perpendicular to the rotor axis. Clearance between the rotor and the pan is adjustable to change the maximum size of the crusher output. As the bits wear, they can be extended out from the rotor with an adjusting rod. The DBT roll impactor is available with feed openings ranging from 40 x 40 in. to 72 x 72 in. Capacities range from 450 to 1,500 tph, the company says.
InfoDirect 703

4. Eagle Crusher Co.
Eagle Crusher Co.’s UltraMax Series of primary and secondary impactors feature solid steel, three-bar sculptured rotors that combine the high inertia of solid rotors with the low wear associated with open-rotor designs, according to the company. Rotor design and an engineered feed angle optimize rotor penetration of feed materials to produce a more controlled impact action, Eagle says. A one-piece, gravity-hung primary curtain is reversible; the secondary curtain has interchangeable liners. Ultra-chrome titanium blow bars are available to reduce wear costs in some applications. UltraMax Series impactor capacities range from 60 to 600 tph, according to the company.
InfoDirect 704

5. Extec
Extec’s track-mounted impactor plant incorporates a Krupp Hazemag impactor box with a 50- x 37-in. feed opening. The crusher operates on diesel hydraulic power with a Deutz 365-hp engine and hydraulic transmission without clutches. The speed of the impactor can be varied between 500 and 860 rpm. A large impactor box and a “fast track” system ensures a clear flow of reinforcing bar when crushing concrete, the company says.
InfoDirect 705

6. Grasan
Grasan primary impactor plants include the KRH1515 and KRH1620. The company uses Hazemag APPH impactors on its plants featuring fully automatic, hydraulic cylinder systems for breaker plate adjustment. The KRH1515, with a rated capacity of more than 500 tph, has a 45- x 60-in. feed opening and a hydraulic moveable inlet base to help clear jamming and bridging. Crusher side liners are in three standardized shapes and all multi-blocks are interchangeable. The KRH1620 can reduce 24-in. limestone to 6-in.-minus material in one step at up to 850 tph, Grasan says. It has a 50- x 80-in. inlet to accommodate materials up to 36-in. cube.
InfoDirect 706

7. Hazemag USA
Hazemag’s APPH impactor uses a computer-controlled hydraulic apron adjustment to provide continuous control of product sizing, the company says. Aprons are not gravity hung. To handle overloading or large feed materials, aprons only retract when the static load resistance is overcome, then return automatically to the preset gap adjustment. Multiblocks on the inlet base section, front apron, rear apron and rear wall are interchangeable. In addition, wear liners have been standardized to one shape. Hazemag recently developed a GSK-type, six-bar rotor for lower abrasive, lower strength limestone up to 60-in. Blow bars are clamped into the rotor body and secured with a mechanical wedge locking system. Bars can be rotated one time.
InfoDirect 707

8. Kolberg-Pioneer
Kolberg-Pioneer offers several models of New Holland-style and Andreas-style HSIs. Easy apron adjustment and speed selection provides precise gradation control, the company says. Its Andreas style impactors feature a reversible primary apron with replaceable wear edges, a wedge-style blow bar retention system, and a housing that opens hydraulically over center. Kolberg-Pioneer uses what it calls a sculptured Maximum Productivity Rotor in its Andreas-style HSIs that has the largest exposed blow bar area in the industry, with clearances of an open rotor design but the mass of a solid rotor, according to the company.
InfoDirect 708

9. Lippmann-Milwaukee
Lippmann-Milwaukee’s range of portable HSI self-contained plants feature its five models of primary and secondary Andreas-style impactors. The crushers use three-bar solid steel or semi-closed rotors, depending on the model. The blow bar locking system incorporates a jacking assembly that causes all the bars and backing beams to act as a solid mass when struck, according to the company, which allows use of more wear resistant, higher chrome blow bars. Blow bars are rotated and flipped to take advantage of four crushing positions. Frame and apron liners are drilled and tapped to use standard hex-head cap screws. Primary aprons are gravity hung and secondary aprons are spring loaded. A third apron is optional.
InfoDirect 709

10. Metso Minerals
Metso Minerals offers 10 models in its NP series of primary and secondary HSIs. Feed openings range from 30 x 32 in. (maximum feed size of 20 in.) to 94.5 x 75.6 in. (maximum feed size of 59 in.). Metso says it has redesigned the rotor to increase swing weight, improve crushing reduction, and obtain extra capacity. NP impactors use identical rotors for primary and secondary crushers. A single wedge assembly provides high tightening torque and helps eliminate gaps between the rotor and hammers, which reduces the risk of hammer breakage, according to the company. Hammers can be changed vertically or horizontally. Additionally, Metso says no significant modification to the NP impactor is required to change applications — add options like hydraulic assistance, hydraulic adjustment, or a third breaker plate; or use of different grades of steel for hammers or liners. NP impactors are used on tire-mounted portable plants as well as track mounted. NP1315 and NP1415 are used on Metso’s mobile crushers, LT1315 and LT1415, respectively.
InfoDirect 710

11. Sandvik Rock Processing
Sandvik Rock Processing’s North American operation introduces the Impactmaster P- and S-series lines of primary and secondary HSIs. The crushers feature an all-welded frame with two gravity-hung aprons that are independently adjustable with low-profile retaining rods with hydraulic assist but are mounted on a common pivoting shaft. A third curtain is optional on secondary and some large primary models. For parts commonality among all its HSIs, only three sizes of large-diameter rotors are used throughout the entire line of eight P-series and eight S-series crushers. Two different lengths of one-piece, banana-shaped hammers fit the entire range of models. The hammer wedge locking device, single curtain bolt-on bottom liners, and most frame bolt-on liners are common for all units.
InfoDirect 711

12. Stedman
Stedman offers the Mega Slam primary impactor and Grand Slam secondary/tertiary impactor lines and recently introduced hydraulic shim kits to raise and lower the apron assemblies and help maintain gap settings on its crushers. The kits include lift bridge weldments for both front and rear apron assemblies, three-spool control valves to actuate housing cylinders or apron cylinders, shims, counterbalance valves on both cylinders in case one of the hydraulic lines fail, and all necessary hydraulic hoses and fittings.
InfoDirect 712

13. Telsmith
Telsmith offers two styles of HSIs. Three sizes of primary impactors can handle feed sizes up to 60 in. at rates as high as 2,000 tph, Telsmith says. A solid rotor with two or three impellers throws rock against rotating spiral impact bars. Telsmith’s six Andreas-style impactor models have capacities from 30 to 450 tph, the company says. The crushers feature an open-style rotor with a wedge locking system to hold the hammers in place and through flipping and rotation provide four wear surfaces on each hammer. Two aprons adjust independently to control product size. Telsmith recently introduced an optional hydraulic apron adjustment system.
InfoDirect 713

14. Universal Engineering
Universal Engineering offers five models of New Holland-style primary impactors, three models of Andreas-style primary impactors, and a new line of Andreas-style secondary impactors. The new Universal NGS secondary impactor, available in seven sizes, handles feed material up to 16 in. with feed openings up to 26.5 x 91 in. Features include a hydraulic shim adjustment on each of the two gravity-hung impact curtains; a bolt-on feed chute module designed for several feed components, including screens, feeders, and conveyors; interchangeable liners on the interior walls and on the two impact curtains; and a disc-type rotor with S-shaped hammers.
InfoDirect 714

Bob Drake is editor for Aggregates Manager.

Maintenance Matters

Finding Hot Spots for Maintenance

Infrared Thermography can detect electrical and mechanical problems before they cause breakdowns.

By Andy Page

Infrared Thermography (IR) is the science of studying the thermal characteristics of an object to identify abnormalities in the heat signature. Its regular use as a preventive maintenance tool can help aggregate plant operators significantly reduce unplanned downtime. IR can be used in electrical and mechanical applications to identify problems with specific components, usually referred to as hot spots.
Hot spots in electrical switchgear are often caused by loose or dirty connections, a failing overload heater, or an overloaded phase. Hot spots on mechanical components are typically either a lubrication problem or a bearing fault. Problems like these, when detected early, can usually be corrected in a timely and cost efficient manner. Undetected, they can lead to hours or even days of unplanned downtime, lost production and eroding profits.

Figure 1: IR image of a fused disconnect.

Figure 2: IR image of a vertical turbine pump motor.

How Does It Work?
The infrared camera measures the wavelength of the infrared radiation coming from an object. It compares that information to an internal reference and provides a picture containing temperature information. The camera automatically assigns the color black to the coldest thing it sees, the color white to the hottest, and all of the other colors are distributed across the temperature range.
A hot spot is a point on an object that is hotter than similar points on that same object or area. On the fused disconnect in Figure 1, the lower portion of the hinge on the left phase is 106º F hotter than the same spot on the middle and right phases. Since these phases are all constructed from the same material and the electrical loading across all three phases is the same, the temperatures should be within a few degrees of each other. Because of the significant temperature differences, this is a Priority 1 problem, and maintenance should be scheduled as soon as possible.
The darker color (lower temperature) further away from the hinge indicates that the source of the heat is the hinge itself. After the power was disconnected, an inspection revealed that the hinge was loose. After repair of the loose hinge its temperature dropped to within a few degrees of the other two phases.
IR can also be used in mechanical applications, for example to identify bearing faults and lubrication problems. A thorough inspection of motors, gearboxes, pumps, conveyor bearings, etc. during regular operation shows typical temperatures ranging from 10° to 60° F above ambient temperature. Components in similar applications at a given site should display similar thermal characteristics.
The vertical turbine pump motor shown in Figure 2 had an upper bearing temperature of 153° F. Four other vertical turbine pump motors on the same property had upper bearing temperatures of about 120° F. Lubricant in the bearing was at the proper level, so a bearing fault was suspected. Vibration analysis of the bearings confirmed an advanced bearing fault in the motor. The motor was pulled and sent for rebuild. Upon disassembly, the bearing races were found to be badly pitted and at the point of imminent failure.

How and when to inspect
Some companies have chosen to equip and train their own personnel to perform the service. IR Cameras are available from $6,500 to $50,000, depending on options or sophistication. Some companies contract the service to a vendor that specializes in IR Thermography, and some motor rebuild shops offer it as a service. Vendors that specialize in Predictive Maintenance (PdM) and offer IR Thermography as a part of their suite of services are easily found on the Internet.
Whether you choose to contract the service or train your own personnel, make sure that the technician has achieved at least Level 1 certification. Level 1 certification, available through numerous sources, ensures that the technician is fully versed and capable of dealing with all of the issues that typically arise when performing this type of service, including safety issues when dealing with inspection of live electrical apparatus.
IR Thermography scans should be performed at least semi-annually. If the first survey yields a high number of defects, a more frequent survey cycle is recommended until the number of defects drops to less than five per inspection. IR Thermography cannot always identify all of the problems that can arise from electrical switchgear and transmission components, but when used as part of a complete preventive maintenance program, IR can be a powerful tool in the plant manager’s maintenance system.

Andy Page is the managing partner of Page Industries, Ltd. (www.pageindustriesltd.com), an Ohio-based consulting firm specializing in maintenance engineering for the mining and construction aggregates industries. Contact: andy@pageindustriesltd.com or 513-252-7243.